Sheet conveying apparatus and image forming apparatus provided with same

Abstract

A sheet conveying apparatus includes a casing with an internal space, a sheet placing portion, a sheet feeding unit, a driving unit, an opening/closing cover and a drive switching unit. A sheet is to be placed on the sheet placing portion. The sheet feeding unit includes a sheet feeding member. The driving unit is arranged in the internal space and coupled to a rotational drive system of the sheet feeding member and transmits a rotational drive force to the sheet feeding member. The opening/closing cover is openably and closably arranged on the casing to cover a opening formed in the casing. The drive switching unit uncouples the driving unit and the sheet feeding member in association with a switching movement of the opening/closing cover from a closed state to the open state. The sheet feeding unit is mountable into and removable from the internal space through the opening.

What is claimed is: 
     
       1. A sheet conveying apparatus, comprising:
 a casing with an internal space; 
 a sheet placing portion which is arranged in the internal space and on which a sheet is to be placed; 
 a sheet feeding unit which is arranged in the internal space to face the sheet and includes a sheet feeding member having a rotational drive system for conveying the sheet in a predetermined direction by being driven and rotated, the rotational drive system having a first rotary shaft extending in a direction intersecting with mounting and removing directions of the sheet feeding unit; 
 a driving unit which is arranged in the internal space and coupled to the rotational drive system of the sheet feeding member and transmits a rotational drive force to the sheet feeding member, the driving unit including a drive shaft extending coaxially with the first rotary shaft while facing the first rotary shaft when the sheet feeding unit is mounted to the internal space; 
 an opening which is formed in the casing and exposes the sheet feeding unit to the outside of the casing; 
 a cover which is openably and closably arranged on the casing to cover the opening and exposes the sheet feeding unit in an open state; and 
 a drive switching unit which uncouples the driving unit and the sheet feeding member in association with a switching movement of the cover from a closed state to the open state, the drive switching unit uncouples the driving unit and the rotational drive system of the sheet feeding member by uncoupling the first rotary shaft and the drive shaft in an axial direction of the first rotary shaft; 
 wherein the sheet feeding unit is mountable into and removable from the internal space through the opening in the open state of the cover. 
 
     
     
       2. A sheet conveying apparatus according to  claim 1 , wherein:
 the sheet feeding unit includes a holding portion arranged to face the opening and is mountable into and removable from the internal space through the opening. 
 
     
     
       3. A sheet conveying apparatus according to  claim 1 , wherein:
 the opening is formed in an upper surface portion of the casing; and 
 the sheet feeding unit is mountable and removable in a vertical direction through the opening. 
 
     
     
       4. A sheet conveying apparatus according to  claim 1  wherein:
 the first rotary shaft includes a first projection projecting in a radial direction of the first rotary shaft from an end part of the outer circumferential surface of the first rotary shaft on the side of the driving unit; 
 the drive shaft includes a second projection which projects in a radial direction of the drive shaft from the outer circumferential surface of the drive shaft; 
 the driving unit includes a cylindrical portion which is fitted onto the drive shaft slidably and into which the first rotary shaft is inserted when the sheet feeding unit is mounted to the internal space; the cylindrical portion includes a cut portion which is formed by cutting the circumferential surface of the cylindrical portion in the axial direction from an end edge facing the first rotary shaft and with which the second projection is to be engaged; 
 when the sheet feeding unit is mounted to the internal space and the first rotary shaft is inserted into the cylindrical portion, a rotational drive force is transmitted from the drive shaft to the first rotary shaft and the first rotary shaft is integrally rotated with the drive shaft by the engagement of the first projection with the cut portion; and 
 the drive switching unit uncouples the drive shaft from the first rotary shaft by moving the cylindrical portion in the axial direction to separate the first projection from the cut portion. 
 
     
     
       5. A sheet conveying apparatus according to  claim 4 , further comprising:
 a wall portion which is arranged to face a end surface of the cylindrical portion opposite to the first rotary shaft on the drive shaft; and 
 a spring member through which the drive shaft is inserted and which is compressively arranged between the end surface of the cylindrical portion and the wall portion and which biases the cylindrical portion toward the first rotary shaft; 
 wherein the drive switching unit separates the first projection from the cut portion by relatively moving the cylindrical portion in the axial direction with respect to the drive shaft while compressing the spring member. 
 
     
     
       6. A sheet conveying apparatus according to  claim 4 , wherein the drive switching unit includes:
 a second rotary shaft which extends in a direction intersecting with the first rotary shaft in the casing; and 
 a first contact member which is rotatable about the second rotary shaft and displaceable between a first position where the first contact member is separated from the cylindrical portion in the closed state of the cover to engage the cut portion and the first projection and a second position where the first contact member separates the first projection from the cut portion by coming into contact with the cylindrical portion and moving the cylindrical portion in the axial direction according to the switching movement of the cover from the closed state to the open state. 
 
     
     
       7. A sheet conveying apparatus according to  claim 6 , wherein:
 the cover is rotatably supported on a third rotary shaft extending in a direction intersecting with the first rotary shaft in the casing and can be changed the state thereof between the open state and the closed state by the rotation of one end of the cover about the third rotary shaft; 
 the cylindrical portion includes a flange portion connected consecutively to the end surface and projecting in a radial direction of the cylindrical portion; and 
 the drive switching unit includes:
 a rotating member which extends along the drive shaft and the rotating member includes; a base plate portion rotatable about the second rotary shaft, a first contact member connected to the base plate portion and arranged to be able to come into contact with the flange portion and a contacted portion arranged on the base plate portion; and 
 a second contact member which is rotatable about the third rotary shaft, extends along the cover in the closed state of the cover, and projects toward the internal space and is engaged with the contacted portion of the rotating member to move the first contact member to the second position in the open state of the cover. 
 
 
     
     
       8. A sheet conveying apparatus according to  claim 1  wherein:
 the sheet feeding unit includes: 
 a cover member which covers the sheet feeding member; and 
 a bearing portion which is provided on the cover member and through which the first rotary shaft of the sheet feeding member is to be inserted; 
 wherein the sheet feeding unit further comprises a bearing mounting portion arranged to be mounted the bearing portion thereon is further provided in the internal space of the casing; and 
 the sheet feeding unit is mounted into the internal space by fitting the bearing portion into the bearing mounting portion. 
 
     
     
       9. An image forming apparatus, comprising:
 a sheet conveying apparatus for conveying a sheet; and 
 an image forming unit for forming an image on the sheet; 
 wherein the sheet conveying apparatus includes: 
 a casing with an internal space; 
 a sheet placing portion which is arranged in the internal space and on which a sheet is to be placed; 
 a sheet feeding unit which is arranged in the internal space to face the sheet and includes a sheet feeding member having a rotational drive system for conveying the sheet in a predetermined direction by being driven and rotated, the rotational drive system having a first rotary shaft extending in a direction intersecting with mounting and removing directions of the sheet feeding unit; 
 a driving unit which is arranged in the internal space and coupled to the rotational drive system of the sheet feeding member and transmits a rotational drive force to the sheet feeding member, the driving unit including a drive shaft extending coaxially with the first rotary shaft while facing the first rotary shaft when the sheet feeding unit is mounted to the internal space; 
 an opening which is formed in the casing and exposes the sheet feeding unit to the outside of the casing; 
 a cover which is openably and closably arranged on the casing to cover the opening and exposes the sheet feeding unit in an open state; and 
 a drive switching unit which uncouples the driving unit and the sheet feeding member in association with a switching movement of the cover from a closed state to the open state, the drive switching unit uncouples the driving unit and the rotational drive system of the sheet feeding member by uncoupling the first rotary shaft and the drive shaft in an axial direction of the first rotary shaft; 
 wherein the sheet feeding unit is mountable into and removable from the internal space through the opening in the open state of the cover. 
 
     
     
       10. An image forming apparatus according to  claim 9 , wherein:
 the sheet feeding unit includes a holding portion arranged to face the opening and is mountable into and removable from the internal space through the opening. 
 
     
     
       11. An image forming apparatus according to  claim 9 , wherein:
 the opening is formed in an upper surface portion of the casing; and 
 the sheet feeding unit is mountable and removable in a vertical direction through the opening. 
 
     
     
       12. An image forming apparatus according to  claim 9 , wherein:
 the first rotary shaft includes a first projection projecting in a radial direction of the first rotary shaft from an end part of the outer circumferential surface of the first rotary shaft on the side of the driving unit; 
 the drive shaft includes a second projection which projects in a radial direction of the drive shaft from the outer circumferential surface of the drive shaft; 
 the driving unit includes a cylindrical portion which is fitted onto the drive shaft slidably and into which the first rotary shaft is inserted when the sheet feeding unit is mounted to the internal space; the cylindrical portion includes a cut portion which is formed by cutting the circumferential surface of the cylindrical portion in the axial direction from an end edge facing the first rotary shaft and with which the second projection is to be engaged; 
 when the sheet feeding unit is mounted to the internal space and the first rotary shaft is inserted into the cylindrical portion, a rotational drive force is transmitted from the drive shaft to the first rotary shaft and the first rotary shaft is integrally rotated with the drive shaft by the engagement of the first projection with the cut portion; and 
 the drive switching unit uncouples the drive shaft from the first rotary shaft by moving the cylindrical portion in the axial direction to separate the first projection from the cut portion. 
 
     
     
       13. An image forming apparatus according to  claim 12 , further comprising:
 a wall portion which is arranged to face a end surface of the cylindrical portion opposite to the first rotary shaft on the drive shaft; and 
 a spring member through which the drive shaft is inserted and which is compressively arranged between the end surface of the cylindrical portion and the wall portion and which biases the cylindrical portion toward the first rotary shaft; 
 wherein the drive switching unit separates the first projection from the cut portion by relatively moving the cylindrical portion in the axial direction with respect to the drive shaft while compressing the spring member. 
 
     
     
       14. An image forming apparatus according to  claim 12 , wherein the drive switching unit includes:
 a second rotary shaft which extends in a direction intersecting with the first rotary shaft in the casing; and 
 a first contact member which is rotatable about the second rotary shaft and displaceable between a first position where the first contact member is separated from the cylindrical portion in the closed state of the cover to engage the cut portion and the first projection and a second position where the first contact member separates the first projection from the cut portion by coming into contact with the cylindrical portion and moving the cylindrical portion in the axial direction according to the switching movement of the cover from the closed state to the open state. 
 
     
     
       15. An image forming apparatus according to  claim 14 , wherein:
 the cover is rotatably supported on a third rotary shaft extending in a direction intersecting with the first rotary shaft in the casing and can be changed the state thereof between the open state and the closed state by the rotation of one end of the cover about the third rotary shaft; 
 the cylindrical portion includes a flange portion connected consecutively to the end surface and projecting in a radial direction of the cylindrical portion; and 
 the drive switching unit includes:
 a rotating member which extends along the drive shaft and the rotating member includes; a base plate portion rotatable about the second rotary shaft, a first contact member connected to the base plate portion and arranged to be able to come into contact with the flange portion and a contacted portion arranged on the base plate portion; and 
 a second contact member which is rotatable about the third rotary shaft, extends along the cover in the closed state of the cover, and projects toward the internal space and is engaged with the contacted portion of the rotating member to move the first contact member to the second position in the open state of the cover. 
 
 
     
     
       16. An image forming apparatus according to  claim 9 , wherein:
 the sheet feeding unit includes:
 a cover member which covers the sheet feeding member; and 
 a bearing portion which is provided on the cover member and through which the first rotary shaft of the sheet feeding member is to be inserted; 
 
 wherein the sheet feeding unit further comprises a bearing mounting portion arranged to be mounted the bearing portion thereon is further provided in the internal space of the casing; and 
 the sheet feeding unit is mounted into the internal space by fitting the bearing portion into the bearing mounting portion.